Angular speed sensor for detecting angular speed

ABSTRACT

A placing member is configured to be supported from an outside by a terminal electrically connected to a terminal electrode, and an X-axis-direction extended portion, a Y-axis-direction extended portion, and a Z-axis-direction extended portion are provided in the terminal. This configuration provides an angular velocity sensor, in which a problem such that Y-axis-direction and Z-axis-direction vibrations applied from the outside cannot be damped is eliminated, and all the vibrations in three axis directions can be damped.

This application is a U.S. national phase application of PCTinternational application PCT/JP2011/000842 filed on Feb. 16, 2011claiming priority based on Japanese application JP2010-033121 filed onFeb. 18, 2010, Japanese application JP2010-207505 filed on Sep. 16, 2010and Japanese application JP2010-207506 filed on Sep. 16, 2010.

BACKGROUND

1. Technical Field

The present invention relates to an angular velocity sensor and anangular velocity and acceleration detecting composite sensor, which areparticularly used in attitude control or a navigation system of a mobilebody, such as an aircraft and a vehicle.

2. Background Art

FIG. 15 is a sectional view of a conventional angular velocity sensor.Referring to FIG. 15, the conventional angular velocity sensor generallyhas a structure, in which angular velocity sensor element 102 and IC 103that controls angular velocity sensor element 102 are disposed inpackage 101. Recently, there has been proposed a structure in which, inorder to suppress transmission of a disturbance vibration applied topackage 101 to angular velocity sensor element 102, angular velocitysensor element 102 is placed in an internal space of package 101 whilesuspended by vibration-proof member 104.

In angular velocity sensor element 102, angular velocity sensor element102 is mounted on vibration-proof member 104 with seat 105 interposedtherebetween in order to ensure a vibrating space to detect an angularvelocity, while a vibration type element is used to detect a flexuralcomponent of the element from a Coriolis force associated with anangular velocity applied about a detection axis when the drivingvibration of the element is performed.

FIG. 16 is a schematic diagram illustrating a vibrating state of theangular velocity sensor element in the conventional angular velocitysensor. Referring to FIG. 16, when angular velocity sensor element 102is mounted on seat 105 placed on a surface of vibration-proof member104, a barycentric position of angular velocity sensor element 102attached to package 101 with vibration-proof member 104 interposedtherebetween is higher than a surface of vibration-proof member 104.Therefore, as illustrated by arrow 106, a flexural vibration is excitedin vibration-proof member 104 in response to the disturbance vibrationapplied to package 101 from an outside, and the flexural vibration ismistakenly detected as an angular velocity of rotation about thedetection axis.

FIG. 17 is an exploded perspective view of the conventional angularvelocity sensor. FIG. 18 is a horizontal sectional view of theconventional angular velocity sensor. FIG. 19 is a perspective view ofan accommodation unit in the conventional angular velocity sensor whenviewed from below. FIG. 20 is a perspective view of a case in theconventional angular velocity sensor when viewed from above. FIG. 21 isa perspective view of the case in the conventional angular velocitysensor when viewed from below.

Referring to FIGS. 17 to 21, in case 230, multilayer circuit board 231having a layer structure including ceramic and a wiring conductor isprovided from an inner bottom surface to an outer bottom surface, andfirst wiring electrode 232 and second wiring electrode 233 are providedin an upper surface of multilayer circuit board 231 as illustrated inFIG. 20. IC 235, which is electrically connected to first wiringelectrode 232 through wire 234 made of gold or aluminum, and capacitor236, which is electrically connected to second wiring electrode 233, areprovided in the upper surface of multilayer circuit board 231. IC 235 isaccommodated in case 230, and processes an output signal outputted fromvibrator 221. As illustrated in FIG. 21, six case electrodes 237 made ofsilver are provided on an outer bottom surface of multilayer circuitboard 231 in case 230. As illustrated in FIG. 20, sidewall 238 made ofceramic is provided in an outer periphery of the upper surface ofmultilayer circuit board 231, and metal frame 239 made of kovar isprovided on the upper surface of sidewall 238. As illustrated in FIG.20, step portion 240 is provided in the inner bottom surface of case230, third wiring electrodes 241 are provided in step portion 240 whilevibrator 221 in FIG. 17 is fixed to step portion 240, and third wiringelectrodes 241 are electrically connected to vibrator 221 through wire234. An opening of case 230 is sealed by a metallic lid 242 such thatthe inside of case 230 becomes a vacuum atmosphere. Accommodation unit243 made of resin is configured such that a direction perpendicular toan opposing board (not illustrated) that is a measured object of theangular velocity is set to a sensing axis of the angular velocity. Case230 is accommodated in accommodation unit 243, and one end of each of atleast three terminals 244, in which the other end is electricallyconnected to vibrator 221, is integrally buried in case 230. Placingunit 245 is provided in substantially parallel to the sensing axis ofthe angular velocity in accommodation unit 243 while located in asubstantial center of accommodation unit 243, and case 230 is placed onplacing unit 245. One end sides of terminals 244 are buried in placingunit 245, and leading end portions 244 a on one end sides of terminals244 are exposed from placing unit 245.

Case 230 is placed on placing unit 245 in accommodation unit 243,whereby case electrodes 237 in case 230 are electrically connected toleading end portions 244 a on one end sides of terminals 244 in placingunit 245. Because leading end portions 244 a on one end sides ofterminals 244 are mechanically connected to case 230, case 230 isconfigured to be supported from an outside by terminals 244 in each ofwhich the other end is integrally buried in accommodation unit 243.

As illustrated in FIG. 19, six electrode recesses 246 are provided inthe outer bottom surface of accommodation unit 243, and the leading endportions on the sides of the other ends of terminals 244, which areintegrally buried in accommodation unit 243, are exposed to electroderecesses 246 to provide supply electrode 247, GND electrode 248, outputelectrode 249, and three fixing electrodes 250. As illustrated in FIG.18, Z-shape bending portion 244 b is provided in the substantial centerof each of six terminals 244, and Y-axis-direction extended portion 251and Z-axis-direction extended portion 252 are provided by bendingportion 244 b, whereby case 230 is configured to be displaced in anX-axis direction with respect to accommodation unit 243. As illustratedin FIG. 19, three recesses 253 are provided in the outer bottom surfaceof accommodation unit 243. As illustrated in FIG. 19, in metallic cover254, three latching pawls 256 are provided on the opening side, and thelatching pawls 256 are swaged at recesses 253 in accommodation unit 243illustrated in FIG. 19, thereby providing GND potential connectionportion 255 in the outer bottom surface of accommodation unit 243 asillustrated in FIG. 19.

An operation of the conventional angular velocity sensor having theabove configuration will be described below.

When vibrator 221 rotates at angular velocity ω about a center axis(sensing axis) in a longitudinal direction while performing flexionmovement at an eigenfrequency, a Coriolis force of F=2 mV×ω is generatedin an arm of vibrator 221. The output signal including a charge isinputted to IC 235 by the Coriolis force through wire 234, third wiringelectrode 241, multilayer circuit board 231, first wiring electrode 232,and wire 234, and waveform processing is performed to the output signal.The output signal is inputted to an target computer (not illustrated)through second wiring electrode 233, capacitor 236, case electrode 237,leading end portion 244 a on one side of terminal 244, terminal 244, andoutput electrode 249 to detect the angular velocity.

Assuming that a vibration in the X-axis direction is applied from theoutside, case 230 is bent in the X-axis direction with respect toaccommodation unit 243 because Y-axis-direction extended portion 251 andZ-axis-direction extended portion 252 are provided in terminal 244 inthe conventional angular velocity sensor. Therefore, theX-axis-direction disturbance vibration applied from the outside isdamped so as not to propagate to case 230.

For example, PTL 2 is well known as citation list information on theinvention of the subject application.

However, in the above conventional configuration, because case 230 isbent in the X-axis direction with respect to accommodation unit 243,although the X-axis-direction disturbance vibration applied from theoutside can be damped so as not to propagate to case 230,Y-axis-direction and Z-axis-direction vibrations applied from theoutside cannot be damped.

FIG. 22 is an exploded perspective view of a conventional angularvelocity and acceleration detecting composite sensor. FIG. 23 is a sidesectional view of the conventional angular velocity and accelerationdetecting composite sensor. FIG. 24 is a perspective view of an angularvelocity detection element in the conventional angular velocity andacceleration detecting composite sensor. FIG. 25 is a perspective viewof the conventional angular velocity and acceleration detectingcomposite sensor.

Referring to FIGS. 22 to 25, angular velocity detector 301 includesvibrating body 302 that is constructed by a tuning fork, in whichsingle-crystal quartz thin films having different crystal axes arebonded to each other as illustrated in FIG. 24, case 303 thataccommodates vibrating body 302, and lid 304 that closes an opening (notillustrated) provided in an upper surface of case 303. Drivingelectrodes 305 are provided on a frontside surface and a backsidesurface of vibrating body 302 constituting angular velocity detector301, and detection electrodes 306 are provided on an outer side surfaceand an inner side surface of vibrating body 302. Case 303 constitutingangular velocity detector 301 accommodates vibrating body 302 therein,and the opening (not illustrated) is provided in the upper surface ofcase 303. As illustrated in FIG. 22, supply terminal 307, angularvelocity output terminal 308, and GND terminal 309 are provided in lid304 constituting angular velocity detector 301 so as to pierce lid 304from the upper surface to the lower surface, and one end of each ofsupply terminal 307 and GND terminal 309 is electrically connected todriving electrode 305 of vibrating body 302. One end of angular velocityoutput terminal 308 provided in lid 304 is electrically connected todetection electrode 306 of vibrating body 302.

In acceleration detector 311 in which an acceleration signal processingIC (not illustrated) is incorporated, a movable electrode plate (notillustrated) and a fixed electrode plate (not illustrated) are provided,and supply terminal 312, X-axis acceleration output terminal 313 a,Y-axis acceleration output terminal 313 b, and GND terminal 314, in eachof which one end is electrically connected to the movable electrodeplate (not illustrated) and the fixed electrode plate (not illustrated),are provided so as to project outward. Reference numeral 315 denotes acircuit board, angular velocity detector 301 is fixed to a lower surfaceof circuit board 315, many terminal insertion holes 316 are made fromthe upper surface to the lower surface of circuit board 315, and supplyterminal 307, angular velocity output terminal 308, and GND terminal 309of angular velocity detector 301 are inserted in terminal insertionholes 316. Acceleration detector 311 is fixed to the lower surface ofcircuit board 315, and angular velocity signal processing IC 317including an electronic component in which an AGC circuit (notillustrated) is provided is provided in the upper surface of circuitboard 315. Supply terminal 307, angular velocity output terminal 308,and GND terminal 309 of angular velocity detector 301 and supplyterminal 312, X-axis acceleration output terminal 313 a, Y-axisacceleration output terminal 313 b, and GND terminal 314 of accelerationdetector 311 are electrically connected to angular velocity signalprocessing IC 317.

Shielded case 318 includes metallic accommodation unit 318 a and lid 318c that closes opening 318 b of accommodation unit 318 a. Shielded case318 accommodates circuit board 315, angular velocity detector 301, andacceleration detector 311 therein, and power relay terminal 319, GNDrelay terminal 320, angular velocity relay terminal 321, X-axisacceleration relay terminal 322, and Y-axis acceleration relay terminal323 are provided in shielded case 318 so as to pierce from the inside tothe outside. In shielded case 318, one end of power relay terminal 319is electrically connected to supply terminal 307 of angular velocitydetector 301 and supply terminal 312 of acceleration detector 311, andone end of GND relay terminal 320 is electrically connected to GNDterminal 309 of angular velocity detector 301 and GND terminal 314 ofacceleration detector 311. One end angular velocity relay terminal 321is electrically connected to angular velocity output terminal 308 ofangular velocity detector 301, one end of X-axis acceleration relayterminal 322 is electrically connected to X-axis acceleration outputterminal 313 a of acceleration detector 311, and one end of Y-axisacceleration relay terminal 323 is electrically connected to Y-axisacceleration output terminal 313 b of acceleration detector 311. Biasingportions 324 constructed by elastic protrusions, each of which is formedby making a cut in a perpendicular portion 318 d, are provided in lid318 c of shielded case 318. Lid 318 c is elastically crimped in an outerside surface of opening 318 b of shielded case 318 by biasing portions324, whereby accommodation unit 318 a is set to the same potential aslid 318 c.

Resin protective case 325 having a cylindrical shape with a bottomaccommodates shielded case 318 therein, connector 326 is provided inprotective case 325 so as to project outward from the side surface, oneend of each of power connector terminal 327, angular velocity connectorterminal 328, X-axis acceleration connector terminal 329, Y-axisacceleration connector terminal 330, and GND connector terminal 331 isprovided inside connector 326, and the other end is buried in protectivecase 325. As illustrated in FIG. 25, through-holes 332 are made inprotective case 325 from the bottom surface to the outer bottom surface,and the other end of each of power connector terminal 327, angularvelocity connector terminal 328, X-axis acceleration connector terminal329, Y-axis acceleration connector terminal 330, and GND connectorterminal 331 is located in through-hole 332 made in protective case 325.The other end of X-axis acceleration relay terminal 322 is inserted in ahole (not illustrated) of X-axis acceleration connector terminal 329 ofprotective case 325, and electrically connected by solder 335. The otherend of Y-axis acceleration relay terminal 323 is inserted in a hole (notillustrated) of Y-axis acceleration connector terminal 330, andelectrically connected by solder 335. The other end of power relayterminal 319 is inserted in a hole (not illustrated) of power connectorterminal 327, and electrically connected by solder 335. The other end ofangular velocity relay terminal 321 is inserted in a hole (notillustrated) of angular velocity connector terminal 328, andelectrically connected by solder 335. The other end of GND relayterminal 320 is inserted in a hole (not illustrated) of GND connectorterminal 331, and electrically connected by solder 335. Resin protectivelid 336 closes the opening provided in the upper surface of protectivecase 325.

An operation of the conventional angular velocity and accelerationdetecting composite sensor configured and assembled as described abovewill be described below.

A DC voltage of an externally-provided power supply (not illustrated) isconverted into an AC voltage by power connector terminal 327, powerrelay terminal 319, and angular velocity signal processing IC 317, andthe AC voltage is applied to driving electrode 305 of vibrating body 302of angular velocity detector 301 through supply terminal 307. Similarly,driving electrode 305 is grounded through GND connector terminal 331,GND relay terminal 320, and GND terminal 309, whereby vibrating body 302performs a flexion vibration. At this point, when angular velocitydetector 301 rotates at angular velocity ω about the center axis in thelongitudinal direction of vibrating body 302, the Coriolis force of F=2mv×ω is generated in vibrating body 302. The output signal including thecharge generated in detection electrode 306 by the Coriolis force isconverted into an output voltage through angular velocity outputterminal 308 by angular velocity signal processing IC 317 of circuitboard 315, and the output voltage is inputted to the target computer(not illustrated) through angular velocity relay terminal 321 andangular velocity connector terminal 328 to detect the angular velocity.Similarly, when the acceleration is applied in the X-axis direction andthe Y-axis direction, which are directions horizontal to a plane ofacceleration detector 311, while 5 V is applied to the movable electrodeplate (not illustrated) and the fixed electrode plate (not illustrated)of acceleration detector 311 through power connector terminal 327, powerrelay terminal 319, and supply terminal 307, the movable electrode plate(not illustrated) moves to change a capacity of a capacitor providedbetween the movable electrode plate (not illustrated) and the fixedelectrode plate (not illustrated). The change in capacity is convertedinto the output voltage in acceleration detector 311, and theacceleration in the X-axis direction is inputted to the target computer(not illustrated) through X-axis acceleration output terminal 313 a,X-axis acceleration relay terminal 322, and X-axis accelerationconnector terminal 329 to detect the acceleration in the X-axisdirection. Similarly, the acceleration in the Y-axis direction isinputted to the target computer (not illustrated) through Y-axisacceleration output terminal 313 b, Y-axis acceleration relay terminal323, and Y-axis acceleration connector terminal 330 to detect theacceleration in the Y-axis direction. The angular velocity applied tothe vehicle body, acceleration in the X-axis direction, and theacceleration in the Y-axis direction are analyzed by the target computer(not illustrated) to analyze a behavior of the vehicle body.

For example, PTL 3 is well known as citation list information on theinvention of the subject application.

However, in the conventional configuration, because supply terminal 307,angular velocity output terminal 308, and GND terminal 309 of angularvelocity detector 301 are rigidly fixed to circuit board 315, theflexion vibration of vibrating body 302 in angular velocity detector 301is directly transmitted to acceleration detector 311 through circuitboard 315. When the movable electrode plate of acceleration detector 311moves, the acceleration output signal is detected even though theacceleration is not generated.

CITATION LIST Patent Literatures

-   PTL 1: Unexamined Japanese Patent Publication No. 2005-331449-   PTL 2: Japanese Translation of PCT Publication No. 03/046479-   PTL 3: Unexamined Japanese Patent Publication No. 2003-4450

SUMMARY

An object of the present invention is to improve detection accuracy ofthe angular velocity sensor.

In the angular velocity sensor in which the angular velocity sensorelement is suspended in the internal space of the package with thevibration-proof member interposed therebetween, the present inventionhas a structure, in which the vibration-proof member is divided into aconnection portion to the package, a connection portion to a seat, and asuspension portion located between the connection portions and a heightin a barycentric position of the suspension portion is matched with aheight in a barycentric position of a composite body including theangular velocity sensor element, the seat, and the connection portion tothe seat in the vibration-proof member.

According to the configuration, the present invention can suppress aninfluence of the disturbance vibration on the angular velocity sensorelement to improve the detection accuracy of the angular velocitysensor.

The present invention provides the angular velocity sensor, in which theproblem such that the Y-axis-direction and Z-axis-direction vibrationsapplied from the outside cannot be damped is eliminated, and all thevibrations in the three axis directions can be damped.

The present invention includes: a tuning-fork type vibrator in which adriving electrode, a detection electrode, and a support portion areprovided; an IC that processes an output signal outputted from thedetection electrode of the vibrator; a placing member that supports thesupport portion of the vibrator; and a case that accommodates thevibrator, the IC, and the placing member therein, a terminal electrodebeing provided in a step portion of the case, a supply electrode, a GNDelectrode, and an output electrode being provided in an outer bottomsurface of the case, a wiring pattern that electrically connects theterminal electrode and the supply electrode, the GND electrode, and theoutput electrode being provided in the case, wherein the placing memberis configured to be supported from an outside by a terminal electricallyconnected to the terminal electrode. An X-axis-direction extendedportion, a Y-axis-direction extended portion, and a Z-axis-directionextended portion are provided in the terminal. According to theconfiguration, because the X-axis-direction extended portion, theY-axis-direction extended portion, and the Z-axis-direction extendedportion are provided in the terminal, the Z-axis-direction vibrationapplied from the outside is damped by the X-axis-direction extendedportion and the Y-axis-direction extended portion, the X-axis-directionvibration applied from the outside is damped by the Y-axis-directionextended portion and the Z-axis-direction extended portion, and theY-axis-direction vibration applied from the outside is damped by theZ-axis-direction extended portion and the X-axis-direction extendedportion. Therefore, all the vibrations in the three axis directions canbe damped.

The present invention also provides an angular velocity and accelerationdetecting composite sensor, in which the problem such that theacceleration output signal is detected even though the acceleration isnot generated by directly transmitting the flexion vibration of thevibrating body in the angular velocity detector to the accelerationdetector is eliminated to improve the reliability.

The present invention includes: a vibrator that detects an angularvelocity; an acceleration sensor element that detects acceleration; anIC that processes an angular velocity output signal generated from thevibrator and an acceleration output signal generated from theacceleration sensor element; and a case that accommodates the vibrator,the acceleration sensor element, and the IC, a terminal electrode beingprovided in an inner side surface of the case, a supply electrode, a GNDelectrode, and an output electrode being provided in an outer bottomsurface of the case, wherein the vibrator is fixed to the case with aterminal interposed therebetween, and the acceleration sensor element isrigidly fixed to the case. According to the configuration, the vibratoris fixed to the case with the terminal interposed therebetween, theacceleration sensor element is rigidly fixed to the case. Therefore, theproblem such that the acceleration output signal is detected even thoughthe acceleration is not generated is eliminated because the flexuralvibration of the vibrator is damped by the terminal and thus thevibration of the vibrator is hardly transmitted to the accelerationsensor element, and the acceleration can accurately be detected becausethe acceleration sensor element is rigidly fixed to the case.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of an angular velocity sensor according to afirst exemplary embodiment of the present invention.

FIG. 2 is a plan view of an angular velocity sensor element constitutingthe angular velocity sensor according to the first exemplary embodimentof the present invention.

FIG. 3 is a view illustrating a structure of an electrode provided inthe angular velocity sensor element constituting the angular velocitysensor according to the first exemplary embodiment of the presentinvention.

FIG. 4 is a schematic diagram illustrating a suspended state of theangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.

FIG. 5 is a plan view of another angular velocity sensor elementconstituting the angular velocity sensor according to the firstexemplary embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating a driving state of anotherangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a detection state of anotherangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.

FIG. 8 is an exploded perspective view of an angular velocity sensoraccording to a second exemplary embodiment of the present invention.

FIG. 9 is a plan view illustrating a state in which a lid of the angularvelocity sensor according to the second exemplary embodiment of thepresent invention is taken off.

FIG. 10 is a bottom view of the angular velocity sensor according to thesecond exemplary embodiment of the present invention.

FIG. 11 is a perspective view of a vibrator in the angular velocitysensor according to the second exemplary embodiment of the presentinvention.

FIG. 12 is a side sectional view of the vibrator in the angular velocitysensor according to the second exemplary embodiment of the presentinvention.

FIG. 13 is a perspective view illustrating a state in which the vibratorand terminals are fixed to a placing member in the angular velocitysensor according to the second exemplary embodiment of the presentinvention.

FIG. 14A is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 14B is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 14C is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 14D is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 14E is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 14F is an assembly process chart of the vibrator in the angularvelocity sensor according to the second exemplary embodiment of thepresent invention.

FIG. 15 is a sectional view of a conventional angular velocity sensor.

FIG. 16 is a schematic diagram illustrating a vibrating state of anangular velocity sensor element in the conventional angular velocitysensor.

FIG. 17 is an exploded perspective view of the conventional angularvelocity sensor.

FIG. 18 is a horizontal sectional view of the conventional angularvelocity sensor.

FIG. 19 is a perspective view of an accommodation unit in theconventional angular velocity sensor when viewed from below.

FIG. 20 is a perspective view of a case in the conventional angularvelocity sensor when viewed from above.

FIG. 21 is a perspective view of the case in the conventional angularvelocity sensor when viewed from below.

FIG. 22 is an exploded perspective view of a conventional angularvelocity and acceleration detecting composite sensor.

FIG. 23 is a side sectional view of the conventional angular velocityand acceleration detecting composite sensor.

FIG. 24 is a perspective view of an angular velocity detection elementin the conventional angular velocity and acceleration detectingcomposite sensor.

FIG. 25 is a perspective view of the conventional angular velocity andacceleration detecting composite sensor.

DESCRIPTION OF EMBODIMENTS First Exemplary Embodiment

Hereinafter, a first exemplary embodiment of the present invention willbe described with reference to the drawings.

FIG. 1 is a sectional view of an angular velocity sensor according to afirst exemplary embodiment of the present invention. Referring to FIG.1, in a basic structure of the angular velocity sensor of the firstexemplary embodiment, angular velocity sensor element 2 and IC 3 aredisposed in an internal space of package 1 made of laminated ceramic,and an opening of package 1 is sealed by lid 7. IC 3 includes a drivecontrol circuit that applies a driving signal to angular velocity sensorelement 2 and a detection circuit that processes a detection signaloutputted from angular velocity sensor element 2.

Angular velocity sensor element 2 has a structure in which angularvelocity sensor element 2 is supported by seat 9, which is suspended inthe internal space of package 1 by vibration-proof member 8 made of aflexible plate-spring material or a flexible elastic material, such thatthe disturbance vibration is not transmitted through package 1.

FIG. 2 is a plan view of the angular velocity sensor elementconstituting the angular velocity sensor according to the firstexemplary embodiment of the present invention. Referring to FIG. 2,angular velocity sensor element 2 is a tuning-fork type vibrationelement in which driving electrodes 2 c and sensing electrodes 2 d areprovided on a pair of driving arms 2 b extended along detection axis 10from support portion 2 a, and angular velocity sensor element 2 has astructure, in which a portion on which angular velocity sensor element 2is mounted in seat 9 is formed into a step structure as illustrated inFIG. 1 and support portion 2 a of angular velocity sensor element 2 ismounted on an upper step surface 9 a to ensure a vibrating space ofdriving arm 2 b.

FIG. 3 is a view illustrating a structure of an electrode provided inthe angular velocity sensor element constituting the angular velocitysensor according to the first exemplary embodiment of the presentinvention. Referring to FIG. 3, angular velocity sensor element 2 isconstructed by a substrate made of Si, a structure of each electrodeprovided on a surface of the Si substrate is formed by upper electrode11 a made of Au, lower electrode 11 b made of Pt, and piezoelectric bodylayer 11 c, which is disposed between upper electrode 11 a and lowerelectrode 11 b and made of PZT. When a positive voltage is applied toupper electrode 11 a while lower electrode 11 b is grounded, acompression force acts in a direction in which the electrodes arelaminated, and a stress is generated by the compression force in adirection in which an electrode pattern extends. On the other hand, whena negative voltage is applied, a tension force acts on the electrode,and the stress is generated by the tension force in a direction in whichthe electrode pattern shrinks. On the contrary, the electrode shrinks bythe flexion of the driving arm 2 b to generate the negative voltage, andthe electrode extends to generate the positive voltage.

As to the detection of the angular velocity, a driving voltage isapplied to driving electrode 2 c as illustrated in FIG. 2 from IC 3 toperform a driving vibration of driving arm 2 b in an X-axis direction asillustrated by an arrow, namely, in a direction in which driving arms 2b are provided in parallel. In the driving vibration state, the angularvelocity is applied about the detection axis to generate a flexuralvibration of driving arm 2 b by a Coriolis force in a Z-axis direction(a direction orthogonal to a vibration plane (XY-plane) formed by thedriving vibration), the flexural vibration is converted into an electricsignal by sensing electrode 2 d, and the electric signal is outputted toIC 3.

FIG. 4 is a schematic diagram illustrating a suspended state of theangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.Referring to FIG. 4, vibration-proof member 8 has a step structureincluding surface 8 a and surface 8 b. Surface 8 a is parallel to thevibration plane (XY-plane) in the driving vibration of angular velocitysensor element 2, and surface 8 b is orthogonal to the vibration plane(XY-plane). In the structure of vibration-proof member 8, thedisturbance vibration in the direction (Z-axis direction) orthogonal tothe vibration direction is suppressed by a vibration-proof effect ofsurface 8 a parallel to the vibration plane (XY-plane), and thedisturbance vibration in the direction (in-plane direction in theXY-plane) parallel to the vibration plane is suppressed by avibration-proof effect of surface 8 b orthogonal to the vibration plane(XY-plane).

In the angular velocity sensor, an outside portion of vibration-proofmember 8 is connected to package 1 as connection portion 8 c, an insideportion of vibration-proof member 8 is connected to seat 9 as connectionportion 8 d, and a height of barycentric position 12 of suspensionportion 8 e between connection portions 8 c and 8 d is matched with aheight of barycentric position 13 of a composite body including angularvelocity sensor element 2, seat 9, and connection portion 8 d to seat 9,namely, a whole portion suspended by suspension portion 8 e, therebyimproving detection accuracy of the angular velocity sensor. As usedherein, “the heights of barycentric positions 12 and 13 are matched witheach other” means that the relative heights of the barycentric positionsare matched based on the vibration plane in the driving vibration ofangular velocity sensor element 2.

That is, when the height of barycentric position 12 of suspensionportion 8 e is matched with the height of barycentric position 13 of thecomposite body suspended by suspension portion 8 e, the generation ofthe flexion vibration indicated by arrow 106 is suppressed in theconfiguration in which the barycentric position of conventional angularvelocity sensor element 102 is located above vibration-proof member 104as described with reference to FIG. 16, and output of an unnecessarydetection signal of the disturbance vibration can be suppressed. As aresult, the detection accuracy of the angular velocity sensor can beenhanced.

Although not illustrated, when vibration-proof member 8 has a flatstructure, the same effect is obtained such that the height ofbarycentric position 12 of suspension portion 8 e is matched with theheight of barycentric position 13 of the composite body includingangular velocity sensor element 2 suspended by suspension portion 8 e.

In angular velocity sensor element 2 described in the foregoingdescription, as illustrated in FIG. 2, the detection axis (Y-axis) isparallel to the driving vibration plane (XY-plane) in which the drivingvibration of driving arm 2 b is performed. Alternatively, the angularvelocity sensor having the different detection axial direction may beformed into a substantially same shape using the angular velocity sensorelement in which the detection axis (Z-axis) is orthogonal to thevibration plane (XY-plane).

FIG. 5 is a plan view of another angular velocity sensor elementconstituting the angular velocity sensor according to the firstexemplary embodiment of the present invention. Referring to FIG. 5, inangular velocity sensor element 14 in which the detection axis (Z-axis)is orthogonal to the driving vibration plane (XY-plane), weights 14 bare symmetrically disposed on both sides of fixed portion 14 a locatedin a central portion, weights 14 b are connected by a pair of drivingarms 14 c, and driving electrode 14 d, detection electrode 14 e, andmonitor electrode 14 f which will be described later are disposed ondriving arm 14 c.

FIG. 6 is a schematic diagram illustrating a driving state of anotherangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.FIG. 7 is a schematic diagram illustrating a detection state of anotherangular velocity sensor element constituting the angular velocity sensoraccording to the first exemplary embodiment of the present invention.Referring to FIGS. 6 and 7, the driving signal is applied to drivingelectrode 14 d from IC 3 to perform the driving vibration such thatdriving arm 14 c symmetrically extends and shrinks weight 14 b in thedirection (X-axis direction) in which fixed portion 14 a and weight 14 bare connected. In the driving vibration state, the direction (Z-axisdirection) perpendicular to the vibration plane (XY-plane) of angularvelocity sensor element 14 is set to the detection axis, and the angularvelocity is received about the detection axis to generate the Coriolisforce. Driving arm 14 c vibrates in the direction (Y-axis direction)orthogonal to the driving vibration direction (X-axis direction) by theCoriolis force, a deformation of driving arm 14 c by detection vibrationis sensed by detection electrode 14 e, and the electric signal isoutputted to IC 3. That is, the angular velocity sensor element has thevibration element structure in FIGS. 6 and 7.

Like tuning-fork type angular velocity sensor element 2 illustrated inFIG. 2, angular velocity sensor element 14 has the structure in whichangular velocity sensor element 14 is suspended by vibration-proofmember 8 while the vibrating space is ensured by the seat. Therefore, asillustrated in FIG. 4, the height of barycentric position 12 ofsuspension portion 8 e is matched with the height of barycentricposition 13 of the composite body including angular velocity sensorelement 14, seat 9, and connection portion 8 d to seat 9 invibration-proof member 8, namely, the whole portion suspended bysuspension portion 8 e, which allows the detection accuracy to beenhanced in the angular velocity sensor.

The function of ensuring the vibrating space of angular velocity sensorelement 2 in seat 9 may be formed in vibration-proof member 8. Forexample, although not illustrated, a sheet-like elastic material, suchas a liquid crystal polymer, is integrally molded to form a stepstructure in which angular velocity sensor element 2 is supported so asto be able to vibrate. The step structure acts as seat 9, and thesurrounding sheet portion acts as vibration-proof member 8, so that thenumber of components can be decreased in the angular velocity sensor toimprove productivity. In the configuration in which the composite bodyof vibration-proof member 8 and seat 9 is integrally molded, a thicknessof vibration-proof member 8 is easy to ensure. In this case, thevibration-proof effect can be obtained in the thickness direction(Z-axis direction), and the detection accuracy of the angular velocitysensor can further be enhanced.

The liquid crystal polymer that is used as the elastic memberconstituting vibration-proof member 8 has not only vibration absorbingperformance, but also good fluidity because of a low melting viscosity.Therefore, the liquid crystal polymer is suitable for the molding ofvibration-proof member 8 or the integral molding of the composite bodyof vibration-proof member 8 and seat 9, and use of polyphthalamide (PPA)obtains the same effect.

Alternatively, silicon can also be cited as an example of the elasticmaterial constituting vibration-proof member 8. Silicon has thevibration absorbing performance like the liquid crystal polymer, andsilicon also has an extremely small temperature characteristic of aYoung's modulus. Therefore, the temperature characteristic of theangular velocity sensor can be improved.

When the plate-spring material, such as stainless steel and phosphorbronze, is used as vibration-proof member 8, connection portion 8 d ofvibration-proof member 8 is molded in seat 9 to form an integralstructure. Therefore, suspension portion 8 e having the step structureincluding surface 8 a parallel to the vibration plane (XY-plane) ofangular velocity sensor element 2 and surface 8 b orthogonal to thevibration plane (XY-plane) is made of the plate-spring material, and theproductivity can be improved such that the portion including the stepstructure is made of the elastic material.

Second Exemplary Embodiment

An angular velocity sensor according to a second exemplary embodiment ofthe present invention will be described below.

FIG. 8 is an exploded perspective view of an angular velocity sensoraccording to a second exemplary embodiment of the present invention.FIG. 9 is a plan view illustrating a state in which a lid of the angularvelocity sensor according to the second exemplary embodiment of thepresent invention is taken off. FIG. 10 is a bottom view of the angularvelocity sensor according to the second exemplary embodiment of thepresent invention. FIG. 11 is a perspective view of a vibrator in theangular velocity sensor according to the second exemplary embodiment ofthe present invention. FIG. 12 is a side sectional view of the vibratorin the angular velocity sensor according to the second exemplaryembodiment of the present invention. FIG. 13 is a perspective viewillustrating a state in which the vibrator and terminals are fixed to aplacing member in the angular velocity sensor according to the secondexemplary embodiment of the present invention.

Referring to FIGS. 8 to 13, reference numeral 61 denotes a tuning-forktype vibrator, and vibrator 61 includes first arm portion 61 a, secondarm portion 61 b, and support portion 61 c that connects one end offirst arm portion 61 a and one end of second arm portion 61 b asillustrated in FIG. 11. As illustrated in FIG. 12, in vibrator 61,common GND electrode 63 made of an alloy thin film of Pt and Ti isprovided in a whole upper surface of base material 62 made of Si, andpiezoelectric layer 64 made of a PZT thin film is provided in the uppersurface of common GND electrode 63. As illustrated in FIG. 11, in thetuning-fork type vibrator 61, a pair of first driving electrodes 65 isprovided in the upper surface of piezoelectric layer 64 while locatedinside in the substantial center of the upper surface, and a pair ofsecond driving electrodes 66 is provided in the upper surface ofpiezoelectric layer 64 while located outside in the substantial centerof the upper surface. In vibrator 61, a pair of detection electrodes 67is provided in the upper surface of piezoelectric layer 64 while locatedon a leading end side of the upper surface, and monitor electrode 68 isprovided in the upper surface of piezoelectric layer 64 while located ona base side from first driving electrode 65. GND electrode 69 isprovided in the surface of piezoelectric layer 64 while located in thesurface of support portion 61 c in vibrator 61.

Reference numeral 70 denotes a ceramic case, and case 70 has a layerstructure of ceramic and a wiring conductor from an inner bottom surfaceand an inner side surface to an outer bottom surface, and multilayercircuit board 72 having a wiring pattern (not illustrated) is providedin case 70. Terminal electrode 75 is provided in step portion 74provided in an inner side surface of sidewall 73 of case 70, supplyelectrode 76, GND electrode 77, and output electrode 78 are provided inthe outer bottom surface of case 70, and terminal electrode 75 iselectrically connected to supply electrode 76, GND electrode 77, andoutput electrode 78 by the wiring pattern (not illustrated). Metal frame79 made of kovar is provided on the upper surface of sidewall 73 of case70. Reference numeral 80 denotes a resin placing member, and placingmember 80 supports support portion 61 c of vibrator 61, and is supportedfrom the outside by eight terminals 81 in each of which one end iselectrically connected to terminal electrode 75 of case 70. Each ofterminals 81 includes Y-axis-direction extended portion 82,Z-axis-direction extended portion 83, and X-axis-direction extendedportion 84. In eight terminals 81, X-axis-direction extended portions 84of four terminals 81 disposed outside are extended in a frontsidedirection, and X-axis-direction extended portions 84 of four terminals81 disposed inside are extended in a backside direction. That is, thebarycenter of placing member 80 is substantially matched with the sum ofbarycenters of eight terminals 81.

The X-axis-direction extended portions of eight terminals 81 arealternately extended in the frontside direction and the backsidedirection, whereby the barycenters of terminals 81 are substantiallymatched with the barycenter of placing member 80. Therefore,advantageously the upward or downward movement of vibrator 61, which iscaused by baricentric movements of plural terminals in applying theangular velocity is applied in the Y-axis direction and the Z-axisdirection, is eliminated to stabilize the signal generated from vibrator61.

First driving electrode 65, second driving electrode 66, detectionelectrode 67, and GND electrode 69 of vibrator 61 are electricallyconnected to terminals 81 by wires 85. Reference numeral 86 denotes aresin reinforcing member, and reinforcing member 86 is provided so as tocover a connection point of terminal 81 and terminal electrode 75 ofcase 70, thereby burying terminal 81 in case 70.

Because terminal 81 connected to terminal electrode 75 of case 70 isburied in case 70, the connection of terminal electrode 75 and terminal81 is strengthened, and therefore advantageously the electric connectionbetween terminal electrode 75 and terminal 81 can be ensured even if thestrong vibration is applied to the angular velocity sensor.

Reference numeral 87 denotes an acceleration sensor element, andacceleration sensor element 87 is provided in the inner bottom surfaceof case 70, and electrically connected to terminal electrode 75 by wire85. Reference numeral 88 denotes an IC, and IC 88 is provided in theinner bottom surface of case 70 in parallel to acceleration sensorelement 87, and IC 88 processes the output signal from vibrator 61 andthe output signal from acceleration sensor element 87. Reference numeral89 denotes a lid made of kovar, and lid 89 closes the opening of case70.

A method for assembling the angular velocity sensor according to thesecond exemplary embodiment of the present invention having the aboveconfiguration will be described below.

FIGS. 14A to 14F are assembly process charts of the vibrator in theangular velocity sensor according to the second exemplary embodiment ofthe present invention. As illustrated in FIGS. 14A to 14F, asillustrated in FIG. 14B, common GND electrode 63 made of an alloy thinfilm of Pt and Ti is first formed by evaporation on the upper surface ofpreviously-prepared base material 62 made of Si illustrated in FIG. 14A.Then, as illustrated in FIG. 14C, piezoelectric layer 64 made of a PZTthin film is formed by the evaporation on the upper surface of commonGND electrode 63.

Subsequently, as illustrated in FIG. 14D, forming electrode 65 a made ofan alloy thin film of Ti and Au is formed by evaporation on the uppersurface of piezoelectric layer 64. Then, as illustrated in FIG. 14E,unnecessary points of common GND electrode 63, piezoelectric layer 64,and forming electrode 65 a are removed such that a predetermined shapeis obtained, and first driving electrode 65, second driving electrode66, detection electrode 67, monitor electrode 68, and GND electrode 69are formed on the upper surface of piezoelectric layer 64.

Then, while a voltage is applied to the side of common GND electrode 63,first driving electrode 65, second driving electrode 66, detectionelectrode 67, monitor electrode 68, and GND electrode 69 are grounded topolarize piezoelectric layer 64.

Subsequently, as illustrated in FIG. 14F, individual vibrators 61 areformed by removing the unnecessary points of base material 62.

After sidewall 73 and step portion 74, which are made of ceramic, areformed in a whole outer periphery of an upper surface of multilayercircuit board 72 including a previously-prepared ceramic insulator (notillustrated) and a previously-prepared wiring conductor (notillustrated), terminal electrode 75 made of Au is formed on the uppersurface of the step portion 74, and metal frame 79 made of kovar isfixed to the upper surface of sidewall 73.

Then, supply electrode 76, GND electrode 77, and output electrode 78,which are made of Ag, are formed on the lower surface of multilayercircuit board 72.

IC 88 is mounted on the upper surface of multilayer circuit board 72 ofcase 70, and then IC 88 and multilayer circuit board 72 are electricallyconnected.

After acceleration sensor element 87 is mounted on the upper surface ofmultilayer circuit board 72 of case 70 so as to be provided in parallelto IC 88, acceleration sensor element 87 and terminal electrode 75 ofcase 70 are electrically connected through wire 85 made of aluminum bywire bonding.

After insert molding of eight terminals 81 in placing member 80 isperformed, the lower surface of the support portion 61 c of vibrator 61is fixed to placing member 80, and then first driving electrode 65,second driving electrode 66, detection electrode 67, monitor electrode68, and GND electrode 69, which are formed on the upper surface ofvibrator 61, are electrically connected to terminals 81 through wires 85made of aluminum by wire bonding.

After eight terminals 81 are soldered to terminal electrodes 75 of case70, terminals 81 are buried in case 70 by covering terminals 81 withresin reinforcing member 86.

Then, metallic lid 89 is fixed to the opening of case 70 in a nitrogenatmosphere by seam welding.

An operation of the angular velocity sensor according to the secondexemplary embodiment of the present invention having the aboveconfiguration will be described below.

When the negative voltage is applied to second driving electrode 66while the positive voltage is applied to first arm portion 61 a oftuning-fork type vibrator 61 and first driving electrodes 65 provided infirst arm portion 61 a, first arm portion 61 a and second arm portion 61b of vibrator 61 are opened outward because piezoelectric layer 64located below second driving electrode 66 shrinks while piezoelectriclayer 64 located below first driving electrode 65 extends.

When the positive voltage is applied to second driving electrode 66while the negative voltage is applied to first arm portion 61 a oftuning-fork type vibrator 61 and first driving electrodes 65 provided infirst arm portion 61 a, first arm portion 61 a and second arm portion 61b of vibrator 61 are closed inward because piezoelectric layer 64located below second driving electrode 66 extends while piezoelectriclayer 64 located below first driving electrode 65 shrinks. That is, whenthe AC voltage is applied to first driving electrode 65 and seconddriving electrode 66 of the tuning-fork type vibrator 61, first armportion 61 a and second arm portion 61 b of the vibrator 61 performflexion movement having an eigenfrequency in the in-plane direction at avelocity V. In the flexion movement of vibrator 61, the voltage appliedto first driving electrode 65 and second driving electrode 66 isadjusted such that the output signal generated from monitor electrode 68is kept constant, thereby controlling an amplitude of the flexionvibration.

When vibrator 61 rotates at angular velocity ω about the center axis(sensing axis) in the longitudinal direction while first arm portion 61a and second arm portion 61 b of vibrator 61 perform the flexionmovement at the eigenfrequency, the Coriolis force of F=2 mV×ω isgenerated in the arms of first arm portion 61 a and second arm portion61 b of vibrator 61. The output signal including the charge, which isgenerated by the Coriolis force in piezoelectric layer 64 located belowdetection electrode 67, is inputted to IC 88 through detection electrode67, wire 85, terminal electrode 75, and the wiring pattern (notillustrated) of case 70, and the waveform processing is performed to theoutput signal. Then, the output signal of the angular velocity isoutputted to the outside from output electrode 78 of case 70.

When the acceleration is applied to the angular velocity andacceleration detecting composite sensor, the output signal is generatedin acceleration sensor element 87 according to the acceleration. Afterthe signal processing of the output signal is performed by IC 88 throughmultilayer circuit board 72, terminal electrode 75, and wire 85, theoutput signal is inputted to terminal electrode 75 through wire 85 andinputted to the target computer (not illustrated) through multilayercircuit board 72 and output electrode 78, thereby detecting theacceleration.

At this point, it is assumed that the disturbance vibration of about 25kHz is applied in the Z-axis direction from the outside.

In terminal 81, the Z-axis-direction vibration applied from the outsideis damped by X-axis-direction extended portion 84 and Y-axis-directionextended portion 82.

Similarly, when the disturbance vibration of about 25 kHz is applied inthe X-axis direction from the outside, the X-axis-direction vibrationapplied from the outside is damped by Y-axis-direction extended portion82 and Z-axis-direction extended portion 83.

When the disturbance vibration of about 25 kHz is applied in the Y-axisdirection from the outside, the Y-axis-direction vibration applied fromthe outside can be damped by Z-axis-direction extended portion 83 andX-axis-direction extended portion 84.

That is, in an angular velocity sensor of an exemplary embodiment of thepresent invention, because X-axis-direction extended portion 84,Y-axis-direction extended portion 82, and Z-axis-direction extendedportion 83 are provided in terminal 81, the Z-axis-direction vibrationapplied from the outside is damped by X-axis-direction extended portion84 and Y-axis-direction extended portion 82, the X-axis-directionvibration applied from the outside is damped by Y-axis-directionextended portion 82 and Z-axis-direction extended portion 83, and theY-axis-direction vibration applied from the outside is damped byZ-axis-direction extended portion 83 and X-axis-direction extendedportion 84, and all the vibrations in the three axis directions can bedamped.

The angular velocity sensor of the present invention has the effect tobe able to improve the detection accuracy of the angular velocity sensorelement, and is particularly useful in the in-vehicle angular velocitysensor.

Moreover, the present invention advantageously provides the angularvelocity sensor, in which the problem such that the Y-axis-direction andZ-axis-direction vibrations applied from the outside cannot be damped iseliminated, and all the vibrations in the three axis directions can bedamped. Particularly, the angular velocity sensor of the presentinvention is useful in the attitude control and navigation system of themobile body, such as the aircraft and the vehicle.

Furthermore, the present invention advantageously provides an angularvelocity and acceleration detecting composite sensor, in which theproblem such that the acceleration output signal is detected even thoughthe acceleration is not generated by directly transmitting the flexionvibration of the vibrating body in the angular velocity detector to theacceleration detector is eliminated to improve the reliability.Particularly, the angular velocity and acceleration detecting compositesensor of the present invention is useful in the attitude control andnavigation system of the mobile body, such as the aircraft and thevehicle.

What is claimed is:
 1. An angular velocity sensor comprising: a package;an angular velocity sensor element disposed in the package and having avibration plane; a seat that supports the angular velocity sensorelement to ensure a vibrating space of the angular velocity sensorelement; and a vibration-proof member that suspends the seat in aninternal space of the package, wherein the vibration-proof memberincludes: a connection portion to the package; and a suspension portionlocated between the connection portion and a connection portion to theseat, and a height of a barycentric position of the suspension portionis matched with a height of a barycentric position of a composite bodyincluding the angular velocity sensor element, the seat, and connectionportion to the seat in the vibration-proof member; wherein thesuspension portion has a step-shaped structure including a first surfaceand a second surface, the first surface disposed parallel to thevibration plane of the angular velocity sensor and the second surfacedisposed orthogonal to the vibration plane of the angular velocitysensor; and wherein the height of the barycentric position of thesuspension portion and the height of the barycentric position of thecomposite body are matched based on the vibration lane in a drivingvibration of the angular velocity sensor element.
 2. The angularvelocity sensor according to claim 1, wherein the vibration-proof memberand the seat are integrally molded using an elastic material.
 3. Theangular velocity sensor according to claim 1, wherein thevibration-proof member is made of a liquid crystal polymer.
 4. Theangular velocity sensor according to claim 1, wherein thevibration-proof member is made of polyphthalamide.
 5. The angularvelocity sensor according to claim 1, wherein the vibration-proof memberis made of silicon.
 6. The angular velocity sensor according to claim 1,wherein the vibration-proof member is made of a plate-spring material,and the connection portion to the seat is molded in the seat.
 7. Theangular velocity sensor according to claim 1, wherein the angularvelocity sensor includes at least two of the vibration-proof memberswhich are disposed on opposite sides of the angular velocity sensorelement in each vibration direction, respectively.